Process of preventing fire by nontoxic substances



T. MIDGLEY, JR

Filed July 5l, 1930 PROCESS oF PREVENTING FIRE BY NoNToXIC sUBsTANcEs Sept. 12, 1933.

f i -|NvENToR ATTORNEY Patented, Sept. 12, 1933 UNITED STATES PATENT OFFICE PROCESS' 0F PREVENTING FIRE BY NONTOXIC SUBSTANCES Application July 31, 1930. Serial No. 472,179

7 Claims.

The object of this invention is to provide an atmospheric environment suitable for sustaining active conscious and intelligent life but which l at the same time will not support combustion.

Heretofore substances which could be added to the atmosphere to create a condition which would not support combustion, thereby eliminating certain lire hazards, have been limited in number and all of them have been so toxic that when used in sufficient quantities to inhibit fire the conditions would not support normal human existence.

I have discovered that halo-derivatives of hydrocarbons containing uorine are suiiiciently non-toxic, and at the same time suiciently powerful as inhibitors of re that they may safely Vbe employed for removing the hazards of fire associated with the accidental liberation of iniiammable substances within substantially closed spaces and at the same time they do not prevent workmen or animals from safely entering such enclosed spaces to remove the combustible substances present. For example GF4 is a compound boiling at about 140 C. and is but slightly less 2 toxic to normal intelligent life than nitrogen.

The addition of small percentages of GF4 produces an atmosphere that will not support combustion but will support normal human life. The

exact proportion of GF4 needed to induce this environment varies with the infiammability of the substances present. For example, 10% concentration of GF4 is an ample safeguard against the combustion of wood, paper and similar solid inflazmnable materials. A higher concentration is generally used where the inammable substance is a volatile liquid, and a still higher concentration may be used where the inammable substanceis a gas. I can create a satisfactory working environment for highly inammable gases by the use of 30% of GF4. What has just been described relative to concentration of GF4 is also true as to the percentage of other halogen compounds which may be employed and the choice of compound can be made to accord with the conditions of use.

This method of creating an enviornment which supports life but inhibits ame is apparently in contrast to the usual method of merely inhibiting a ame by forming a non-combustible gas blanket over the combustible substance, such for example, as in the use of carbon dioxide, nitrogen, and other well-known ame arresters. The desired compound may be chosen from the accompanying charts which are explanatory of the compounds which may be formed which are comprised within the group of halo-derivatives of hydrocarbons containing iluorine in which the halogen may be uorine or another halogen.

In these charts Fig. l shows relative values of compounds of the methane group and Fig. 2 with 60 the key shows relative values of compounds of the ethane group. In Fig. 1, the complete formula for each compound is found by making the halogen substitution for hydrogen in the formula CH4. Any compound in Fig. 2 ma'y be 65 named by substituting in place of the numerals in Fig. 2 the corresponding compounds given in the key, as for example 0.9 is CHa-CClzF and 2.4 The arrows on the charts show increasing combustion inhibitation properties with change in the character of the compound and including an increasing halogen content in proportion to hydrogen content. Another group of arrows show trend of decreasing toxicity.

On a basis of toxicity alone I prefer compounds Z5 which do not have more of the other halogen atoms in the molecule than the fluorine. atoms present. On a basis of flame arresting properties,

I prefer not to use compounds in which more hydrogen atoms are present in the molecule than the total halogen atoms present.

The compounds so chosen are substantially inert to human life when employed in proportion in the atmosphere which will be sufcient to inhibit name, or in slightly greater proportion. The exact nature of the properties exhibited by these compounds which are useful in arresting the iiame is at present unknown.

The method of charting may be employed with other groups of compounds coming within the general formula halo-derivatives of hydrocarbon compounds containing fluorine and including groups having a higher carbon content.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l. Process which comprises adding to the atmosphere surrounding a possible point of combustion a quantity of an organic halo derivative containing iiuorine, and limiting the said quantity added to an amount suiiicient to prevent combustion while supporting the existence of human life.

2. Process which comprises adding to the atmosphere surrounding a possible point of combustion a quantity of an aliphatic organic derivative containing fluorine and limiting the said quantity added to an amount sufcient to prevent combustion while supporting the existence of human life. f

3. Process which comprises adding to the atmosphere surrounding a possible point of combustion a quantity of a halo derivative ofa hydrocarbon containing uorine and limiting the said quantity added to an amount sufficient to prevent combustion while supporting the existence 0f human life.

4. Process which comprises adding to the atmosphere surrounding a possible point of combustion a quantity of a halo derivative of an aliphatic hydrocarbon containing tluorine and limiting the said quantity added to an amount sufcient to prevent combustion while supporting the existence of human life.

5. Process which comprises adding to the atmosphere surrounding a possible point of combustion a quantity of tetrauoro methane and limiting the said quantity added to an amount sumcient to prevent combustion while supporting the existence of human life.

6. Process which comprises adding to the atmosphere surrounding a possible point of combustion a quantity of a halo fluoro derivative of methane and limiting the said quantity added to an amount sufcient to prevent combustion while supporting the existence of human life.

7. Process which comprises adding to the atmosphere surrounding a possible point of combustion a quantity of a halo fiuoro derivative of ethane and limiting the said quantity added to an amount suiicient to prevent combustion while supporting the existence of human life.

'THOMAS MIDGLEY, Jn. 

